Gas supply apparatus



1939- G. M. BOOTH 2,158,976

GAS SUPPLY APPARATUS Filed Aug. 15, 1936 z sneets-sneet 2 0 I O o f 76 l650? q? 7 G6 r i a v V A 71 79 I e; v, 64/ E A; ATTORNEYS.

Patented May 16, 1939 UNITED STATES PATENT OFFICE GAS SUPPLY APPARATUSApplication August 15, 1936, Serial No. 96,242

13 Claims.

high rates of flow, and to accomplish this by controlling theflow-determining negative pressure by means which makes it possible tomaintain a very constant and readily adjustable negative 15 pressure,and to avoid certain disadvantages in.-

herent in suction-controlling means heretofore used for the purpose ofdrawing gas at a controlled rate through a flow-controlling orifice.

The invention has been made especially with the idea of providing an'improved apparatus for introducing gaseous chlorine at a controlled rateinto a minor stream of water to produce a solution to be used for thetreatment of water or sewage or for other purposes. 'In such apparatusin which chlorine gas supplied at a constant substantially atmosphericpressure is drawn through a flow-controlling orifice by a wateraspirator, it has been'the practice to have the pulling capacity of theaspirator somewhat greater than sufficient to draw gas at the maximumdesired rate through the control orifice and to have the excess capacityof the aspirator satisfied by makeup water supplied to the suction inletof the aspirator under a negative head which determines the partialvacuum. or negative pressure available for sucking the gas. In somecases thenegative head under which the make-up water is supplied to theaspirator is constant and the suction transmitted to the control orificeis determined by an adjust- 40 able restriction between the orifice andthe aspirator. In other cases the flow rate of the gas is I varied byvarying the negative head against which the make-up water' is suppliedto the aspirator,

this variation in such negative head being effected either at will orautomatically proportionately to variations in quantity of flowing waterto be treated.

In an apparatus embodying all the features of the present inventionthere is provided automatic means for controlling the pulling c pacityof the aspirator and maintaining such capacity only slightly in excessof that required for sucking in the gas at the desired rate, and apower-operated adjustable'restriction or valve automatically controlledby a negative hydraulic head for determining the suction headtransmitted to the flowcontrolling orifice or other flow-resistingmeans, through which the gas is sucked from aconstant pressure supply,thereby controlling the flow rate of the gas, and means for varying theflow rate of '5 the gas by varying the restriction-controlling negativehead. The desired negative pressure on the down stream side of theflow-controlling oriflee is accurately maintained by the power operatedadjustable restriction, and the pulling capac- 10 ity of the aspiratoris varied and adjusted according to and approximately in proportion tothe amount of gas being drawn through the orifice so that the pullingcapacity of the aspirator is at all times only slightly in excess ofthat required. 1:;

Doing away with the necessity of operating the aspirator at a pullingcapacity greater than sufllcient to draw the gas at a maximum desiredrate and of supplying make-up water to reduce the suction of theaspirator has the advantages of 20 reducing the cost of operation byreducing the amount of water used, and of avoiding the dilution by themake-up water of the solution produced by drawing the gas into theliquid passing through the aspirator. By means of the power- 25 operatedrestriction or valve between the aspirator and'the flow-controllingorifice; a very-accurate control of the negative pressure transmitted tothe orifice is secured, especially when the pulling capacity of 'theaspirator is regulated according 30 to the rate aLwhich ,jghe gas isbeing drawn so as to be at all times only slightly greater thanrequired. The pulling capacity of the aspirator is controlled mostdesirably by regulating the operating pressure of the water supplied tothe 5 aspirator by means of a valve in the supply line.

. By automatically controlling the capacity of the aspirator in thisway, it may be operated by the minimum amount of water required tomaintain the desired negative pressure in the gas passage 40 between theaspirator and the adjustable restriction. This, in addition to itseconomy in use of water, also permits the production of a solution ofthe gas of greater strength than would otherwise be possible. Otherobjects and features of 5 the invention will appear from the followingdescription.

A full understanding of the invention can best be given by a detaileddescription of a chlorine supply apparatus embodying the variousfeatures 50 of the invention in the form now considered best, and such adescription will now be given in connection with the accompanyingdrawings illustrating such an apparatus.

In said drawings;

apparatus; I

Fig. 2 is a similar view oi an alternative form of a part of thecomplete apparatus; and

Fig. 3 shows partly in elevation andpartly in v section an alternativevform or another part of the apparatus. 7

Referring to the drawings, and first to Fig. '1,

. chlorine gas from a suitablesource underapressure, such as a tank ofcompressed liqulfled chlorine, is supplied through a tube Ill to apressure reducing valve ,H by which the gas is sup plied at a constantsubstantially atmospheric pressure to a flow-controlling orifice l2. Thegas is drawn through the flow-controlling oriflce by the suction of awater aspirator l3. A. float chamber I5 is connected between the-orificel2 and the aspirator by passage l6 from'the orifice to the float chamberand passage H from the float chamber to the aspirator, and the outlet l8from the float chamber to the passage H is restricted by afloat-controlled valve IS. in oper-' passage l6, and, therefore, thedesired pressure drop across the orifice, and the operation of the valvecontrolling means is adjustably variable torchanging the negativepressuretransmitted to, the orifice to change the drop in ,pressureacross the orifice and thereby the rate of flow of the gas; andtheoperation of the aspirator is automatically controlled to limit itspulling capacity to that which is only slightly greater than isnecessary to draw the gas throughthe orifice at the desired rate bymaintaining the desired negative pressure in the passage H.

The controlled automatically operating negative pressure controllingvalve Water is raised in the chamber l5 against a negative head byreason of the negative pressure therein, and the valve IS, the positionof which determines the negative controlled by a float 20 in thechamber, the control being such that when by rise -in the water level inthe chamber the float is raised above a predetermined position the valvewill begiven a closing movement to increase the resistance to outflowfrom the chamber and'thereby reduce the vacuum within the chamber andthe passage I 6, and that when by fall of the water level in the chamberthe float moves downward, the valve will be opened to reduce the flowresistance through the outlet, thereby increasing the vacuum in thechamber and in the passage is. The negative head against which the wateris raised by the negative pressure in the chamber thus determines thedegree of vacuum or negative pressure maintained within the chamber and,therefore, the drop in pressure across the orifice.

In order to obtain great accuracy in maintenance of the desired pressurereduction in the chamber l5 and passage l6, means are provided for poweroperation of the valve is under control of the flo'at 20 instead ofhaving the valve operated directly by the float. Y i

Extending downward from the casing of the chamber I5 is a diaphragmcasing 2| in which Pressure maintained in the chamber and transmitted tothe orifice I2, is.

aisaovo Fig.1 is a diagrammatic sectional view of the is mounted anoperating diaphragm 2 2, and

"above and spaced from this diaphragm there I is a'seallng diaphragm23'which forms a sealing partition at the bottom of the float chamberand between the float chamber and the space or chamber 24 between thetwo'diaphragms'. There is a spring 25in the chamber 24 the upper end ofwhich'bears against a flange 26 extendinginwardly from the casingwalland thelower end of whichbears against the diaphragm. 22 and tendsconstantly to 'force the diaphragm downward. 'The valve I9 is connectedto diaphragm 22 by a rod 26 and-tube 2], the rod 26'extending freelythrough a centralopening in the float 20, and the tube 21 extendingthrough and having a watertight connection with the diaphragm 23 andhaving itslower end extended through and secured watertight to thediaphragm 22. stem 28 extends upward from the valve 19 into a suitableguide recess in a part which forms the top wall of the float chamber, I}

The space 30 within. the diaphragm casing beneath the diaphragm servesas a pressure chamber, and in the operation of 'theapparatus thispressure chamber is supplied with a constant small flow of waterthrough. av tube 3| from a source of supply under suitable pressure, thesupply to the chamber being controlled'by a constant flow ratevalve 32which operates to maintain the flow of water into the chamber constantregardle ss oi the pressure within the chamber or the pressure in thetube 3| within the operating limits. When the water'is permitted to flowfree- A guide I 1y from the chamber 30, no pressureis developed againstthe under side of the diaphragm, and the diaphragm is forced downward bythe. spring 25.

through the tube '21, the water beingdischarged into the float chamberl5. From the chamber I5 the water flows through a downwardly ex-'tending tube 33 which connects at its lower end to an upwardlyextending'overflow tube 34, the two together forming a lJ-tube. From theoverflow outlet 35 at the top of the ube .34 the water falls into achamber 40 from which it flows to waste through a tube ll The outflow ofwater. from the pressure chamber 30 through the tube 21 is controlledaccording to the position of the float2ll by a float controlled valve sothat by upward movement of the float the valve is given a closingmovement and by downward movement of the float the valve is given anopening movement. Most desirably, and as shown, the tube 21 has at itsupper end a downwardly opening valve seat 42 to cooperate with a valve43 carried directly by the float.

The water level within the floatchamber I5 is determined by the degreeof vacuum or negative pressure within the chamber and the negative headagainst which water is raised in the chamber. As the water level withinthe chamber l5 determines the position of the float and the floatcontrols the valve I 9, which controls the negative pressure maintainedin the chamber, this negative pressure is determined by the negativehead against which the water is raised in the chamber and may be variedby varying this negative head. This negative head depends on theelevation of the overflow outlet 35 and the air pressure at the outlet.Instead of varying this negative head by varying the elevation of theoverflow'outlet as in the apparatus of the Peet application referred to,the overflow outlet 35 is, in the construction illustrated, fixed, andthe chamber 40 into which the outlet discharges The outflow of waterfrom the chamber 30 is' is a closed chamber, and the desired negativehead is obtained by establishing a suitable negative presurev in thischamber and desired variation in the head is efl'ected by changing thepressure in this chamber. As shown, the overflow outlet 35 is positionedat approximately the normal operating level of the water within thechamber I5." With the overflow outlet so located the shown for thispurpose, and which forms a feature of the m'vention, the tube 4| throughwhich the water ove flowing from the outlet 35 is discharged iromthechamber 40 is a vertical tube large enough so that the amount of waterpassed by the valve '32 and overflowing from the outlet 7 35 will notcause the tube to run entirely full and v 'in the water standing in thechamber 40 of the yet small enough so that the tube will be sealed andthat air will be carried down with the water. Air is thus'exhausted fromthe chamber 40 and apartial vacuum produced in the chamber; and theexact degree of vacuum obtained in the chamberds determinedby the depth01 submergence discharge end of an air inlet tube 44. Air from the tube44 bubbles up through the water and is carried out through thevacuum-creating dis-' charge tube 4 i. The depth of submergence of thedischarge end of the tube 44 will be the measure of the degree ofwvacuummaintained in the chamber 40, and the degree of this vacuum may bevaried by varying the depth of submergence of the discharge end of thetube. To provide for such adjustment, the tube 44 is mounted to extendvertically and to be slidably adjustable through a stufliing box45 inthe top or cover wall When no water-is flowing to the pressure cham-.

ber 30, the spring 25 torces'the diaphragm 22 down until the lower end46 tube 21 seats on a valve head 41 carried. by a screw-adjustable stem48.

Downward movement of, the diaphragm is thus limited, and the valvecloses the tube 21, against .back flow from the chamber l into the watersupply. When the pressure water is admitted to the chamber 30, pressureagainst the under side of the diaphragm 22 overcomes the downward forceof spring 25 and the diaphragm is caused to rise sufliciently to relieveup through the tube 21 the quantity or water passed by valve 32.

In the operation 01 the apparatus as so far described, gas beingsupplied to the control orifice i2 at a constant substantiallyatmospheric pres- .-sure', and the aspirator l2 operating to maintain inthe passage I I a degree of vacuum or negative pressure, in excess ofthat which is to be transmitted to the control oriflce, the negative.pressurezin the chamber and tube f6 andresulting pressure drop acrossoriflce I 2 is controlled by the valve i8. It the degree of vacuum inthe chamber. 15 and tube It is greater than it should be to produce thedesired pressure drop across the orifice and the desired gas flowcorresponding to the degree ofvacuum in the chamber 40, the

produces a pressure rise in the chamber which causes the diaphragm 22 tomove upward to give a slight closing movement to the valve l8, thusreducing the degree of vacuum in the chamber I51 The jupward movement ofthe diaphragm also however, carries the seat 42 at the end of the tube21 slightly away from the valve 43. thereby limiting the increase inpressure in the chamber 30 and causing the diaphragm and parts moved byit, including the valve iii, to come to rest at a position determined bythe float 20. If the degree of vacuum in the chamber [5 and tube [5 isless than it should be, then the water level in the chamber l5 falls anddownward movement of the float moves the valve 43 away from its seat.Resistance to outflow of water from the chamber 30 through the tube 21is thereby reduced, producing a drop in pressure in the chamber 30 whichcauses the diaphragm 22 to move downward to give a slight. openingmovement to the valve l9 which "increases the degree 'of vacuum inchamber i5, and, also, to move the seat 42 toward the valve 43 to limitthe decrease in pressure in chamber'30, thereby causing the diaphragmand parts carried by it, including the valve l9, to come to rest at aposition determined by the float. I The valve l9 will thus beautomatithe chamber l5 andv tube 16 corresponding to the negativepressure in the air vacuum chamber 40; and with the parts arranged asshown, the negative pressure maintained in the chamber 15 will be thesame as that in the'chamber 40.

. The water level in the chamber l5 stays substantially constant, risingand falling only slightly as valve l9 requires adjustment formaintaining the desired negative pressure. in chamber l5. Since thevalve-controlled outlet i8 from the chamber i5 is of relatively largediameter-for the quantity of gas passed, only slight changes in theposition of valve iii are required to control properly over the range ofnegative pressures to be maintained in the chamber ii. The spring 25 hasa low rate (a weight acting on the diaphragm 22 might be substituted) sothat for causing the total required valve adjusting movement of thediaphragm 22 only a slight change in pressure in the chamber isrequired. Only a slight change in the opening through seat 42 isrequired, therefore, for eflecting the slight change required inresistance to the outflow of the water supplied at a constant rate tothe chamber 30. There is thus a substantially fixed relation betweenthe'float 20 and the vacuum control valve l9, only small movements ofthe float being required to cause the small controlling movements of thevalve.

The gas forces acting on the valve I! are negli-* gibly small comparedto the positioning forces acting on the diaphragm 22, and the float iswithout mechanical connection to either the valve or the diaphragm. Theonly reaction tending to change the submergence of the float is thedownward force of the water from the seat 42 on the valve 43, and thisreaction is small and varies only very slightly since the pressure inthe tube 21 varies only very slightly. It is apparent, therefore, thatthe valve i8 follows in its movements very-closely any changes in thewaterlevel in the chamber IS, with the result that the apparatusoperates with a high degree of accuracy in main- .cally adjusted tomaintain a degree of vacuum in taining the desired degree of vacuum inthe cham- 4 outlet 35 is positioned at the operating level of the waterwithin the chamber l5, the drop in pressure across the orifice I2 willequal the degree of vacuum maintained in chamber 45., and

a given pressure drop across the orifice, the degree of vacuummaintained in the chamber l0 should be increased'by anramount equal tothe negative pressure under which the gas is supplied to the orifice, orthe overflow outlet 35 "should be lowered 'a corresponding number ofinches,

, and if the gas is supplied to the orifice at a pressure slightly aboveatmosphere, then for obtaining the given pressure drop'across theorifice the degree of vacuum maintained in the chamber 40 should bereduced or theoverflow outlet 35raised correspondingly.

- The means for controlling the pulling capacityoj charges.

the aspirator The gas pulling capacity of an aspirator, of a given sizedepends on the pressure under which the operating'fluid enters theaspirator and the back pressure against which the aspirator dis- Mostdesirably, as stated, the pulling capacity of the water aspirator'of theapparatus of the present invention is contolled by regulating thepressure under which the water is supplied to the aspirator, andaccording to the invention, the water pressureis automatically soregulated or controlled that 'the pulling capacity of the aspirator isat all times, only. slightly in excess of that required to suck in thegas at the desired rate, whatever that rate may at the time be withinthe operating range of the apparatus. This control is by means of a.valve 50 to which water is supplied through a pipe 5! at suitablepressure not less than the maximum pressure needed for operating theaspirator l3 and from which the water is supplied to the aspiratorthrough a pipe 52 at a pressure determined by the valve.

The valve 50 comprises a seat 55 and a valve disc 56 carried by a stem51 which extends to a diaphragm 58 in a diaphragm casing connected tothe valve casing by a neck having a cylindrical bore in which slides apiston 59 fixed on the stem 51. The piston 59 partitions the valvechamber from th-espace' above the diaphragm, protecting the diaphragmfrom the pressure within the valve chamber, and is of about the samearea as the valve disc sothat any. water pressure on the under side ofthe valve disc tending to move the disc toward its seat is substantiallybalanced by the pressure onthe upper side of the piston. The

'space within the diaphragm casing between thev diaphragm and the pistoniscpen to atmosphere as the drawings-show. Therefore, regardless of itsposition, the opening pressure on the valve disc isapproximatelyproportional to the pressure in the pipe 5| at the inletside of the valve.

Water from a suitable source under pressure, such as the pipe 5| asshown, is supplied to the chamber 6! at the under or outer side of thediaphragm through a tube 62, valve 53 and tube 64. The valve 63 providesa restriction permitting hly a very small flow of water into the tube64,

and is most desirably a constant flow rate'valve similar to valve 32. Ifthe water is permitted to escape freely from the chamber Si or from. the

,on the lever against the downwardforce of the weight oi the water whichmay at any. time be in the valve valve disc 55 to its wide openposition, permitting tube 64' no pressure will build up in the chamber6|, but if the outflow of water from the chamber or pipe 64 isrestricted, pressurewill build up in the chamber and tube to a degreedependenton the resistance to the outflow. A valve 65 controls 5 theoutfiow frpmthe tube 64 and therefore con- I trols the pressure on thediaphragm 58 ten'ding to valve 55 is operated 'by means -,responding tovariations in the amount of water in such container. Inv the apparatusas shown in Fig. 1, a

tube'lll, which is most desirably of small bore, extends upward to thepassage I'I between the chamber I 5 and the aspirator from a'containe'r1| which is hungon' a lever 12 iulcrumed at 13 and to which lever thevalve 65 is connected by means of a rod 14. Al'spring T5 presses upwardon the lever with sufficient force to support the lever in. position toclose the valve 65when the container- H is empty, and additional' upwardpressure on the lever at a' point between its fulcrum and the container.H is provided by a diaphragm 16 connected to the lever by rod 11 andforming one side of a chamber 18 which isconnected by a tube 19 to thepipe 52; The operating pressure of the water flowing to the aspiratorthrough pipe 52 thus reacts through the diaphragm the container 1]. Aconstant small flowof water is supplied to the ontainer ll through atube supplied from the tube 52, the flow into the container beingcontrolled by a constant fiow rate valve 8| which .operates to maintainthe rate of supply of water to the container constant regardless ofvariations in pressure in the tube 62 or other source from which thewater is supplied.

If the l ver I2 is moved downward to open 5 so that the water enteringthrough the valve 63' is freely relieved from tube 54. and no pressure,is built up in the. diaphragm chamber 6|, the inlet water pressure in'pipe 5| forces.

maximum pressure to operate the aspirator. If, on the other hand, byupward movement of the lever 12 the valve 55 is closed, the pressurerises in the diaphragm chamber and the valve 50 is closed and the supplyof water to the aspirator 55 is entirely cut off. In normal operation ofthe apparatus, valves'65 and 56 are both partly open, the pressure underwhich the aspirator is being operated being transmitted through the tube.19 to diaphragm 16 to balance the downward force of the weight oi waterin,container II to hold the lever .12 in an intermediate position, andwater "flowing constantlyinto the container H at a low rate and beingdrawn from the container through pulling capacity of the aspirator hasbeen in- This causes an opening creased to maintaina degree of vacuum,or negative pressure, in the passage I1 suflicient to withdraw throughtube 10 a quantity of water equal to that entering the container.through valve 8|. This negative pressure will be that desired to bemaintained in the passage H as determined by the negative head in tube10.

If, on the other hand, the aspirator is operating with a pullingcapacity suflicient to withdraw water from the container 11 faster thanit enters the container, the weight of water in the container willdecrease and the lever I2 will rise, thereby throttling the valve 65,causing by the diaphragm 16 on the lever, and the lever will againbecome balanced when the operating pressure on the aspirator has beendecreased to a point where its pulling capacity is just sufli-- cient towithdraw waterfrom the container at the same rate that water enters thecontainer, the negative pressure in the passage I! then being thedesired negative pressure determined by the negative head in tube.

The pulling capacity of the aspirator will thus be automaticallyadjusted to be at all times only slightly in excess of that required tomaintain a predetermined negative pressure in the passage 11 for drawingthe gas at a rate determined by the adjustment of the valve l9, and thisautomatic adjustment of the pulling capacity of the aspirator willfollow either a change in adjust ment of the valve I 9 or a change inthe pressure under which water is supplied through the pipe 51. Theaspirator will thus be operated at all times with only a. trifle morethan the minimum amount of water required to develop a pulling capacitysumcient to suck in the gas atthe desiredrate, and all necessity ofoperating the aspirator at the maximum capacity tube a valve whichcontrols the operating pres sure on' the aspirator and thereby itspulling capacity.

In Fig. 2 there is shown means for controlling the pressme on thevalve-controlling diaphragm 58 in .which, instead ofiihaving thecontainer II carried by a lever whic is positioned according to theweight of wat in the container and which positions the valve controllingthe outlet from the' tube 64, thecontainer is stationary and a floatserves to position the valve-positioning lever according to the waterlevel in the container. As shown in Fig. 2, the small flow of waterthrough the tube controlled by the valve 8| is discharged into astationary container Ha from which water is drawn through the tube 10. Afloat in this container is hung by a rod at from one end of a lever 12afulcrumed at 13a and connected at its other end to receive the thrust ofa diaphragm 160 which receives the pressure of water from the tube 19and exerts a force on the lever in opposition to the lift of the float.A valve 65a connected to the lever by a rod 14a controls the outlet fromtube 64 and is so arranged that when by increase-of water in thecontainer the float rises; the lever gives an opening movement of thevalve 65a, and when the amount of water in the container is reduced andthe float fails, a closing movement is given to the valve. This modifiedmeans for controlling the pressure on the diaphragm 58 cooperates withthe apparatus as a whole in the manner described in connection with Fig.1.

Instead of producing apartial vacuum in the vacuum chamber 40 by meansof the overflow tube 4| and determining the exact degree of vacuum inthe chamber by the depth of submergence of the discharge end of the airinlet tube 44, the degree of vacuum in the chamber may be determined andcontrolled by transmitting the desired degree of vacuum to the chamberthrough a connecting tube 95, as shown in Fig. 3. In this way the vacuummaintained in the chamber 40- may'readily be varied to vary the negativehead against'which the water is raised in the float chamber l5, andthereby the flow rate of the chlorine, proportionately to variations inthe quantity of flowing water being treated by the discharge from theaspirator l3, as by connecting the tube to a difierential converter asin the apparatus of the Wallace Patent Nd, 1,777,987. When the rate ofsupply of chlorine is so varied according to variations inflow rate ofwater .to which the chlorine is supplied, the dosage. may be adjusted bymeans of a valve in the connecting passage between the flow-controllingorifice and the float chamber, as shown at 96 in Fig. 3.

What is claimed is:

1. The combination with flow-controlling means and means for supplyinggas at a controlled pressure to the flow-controlling means and a suctiondevice for drawing the gas-through the flow-controlling means, of meansproviding a. restriction in the flow passage between theflow-controlling means and the suction device adjustable for determiningthe negative pressure transmitted to the flow-controlling means, andautomatically acting means for controlling the operation of the suctiondevice to vary its pulling capacity to maintain for difierentadjustments of said restriction a desired negative pressure between thesuction device and said restriction. i. 2. The combination withflow-controlling means and means for supplying gas at a controlledpressure to the flow-controlling means and a suction device for drawingthe gas through the flow-controlling means, of means providingarestriction in the flow passage between the flowcontrolling means andthe suction device adjustable for determining the negative pressuretransmitted to the flow-controlling means, and means responsive to thenegative pressure between the suction device and said restriction forcontrolling. the operation of the suction device to vary itsv pullingcapacity to maintain said negative pres ments 01' said restriction.

3. The combination with flow-controlling means and means for supplyinggas at a con-- stant substantially atmospheric pressure to theflow-controlling means and a suction device for drawing the gas throughthe flow-controlling means, oi means providing an adjustable restrictionin the flow passage between the flow-controlling means and the suctiondevice, means responsive to the negative. pressure between. theflow-controlling means and said restriction and to a control factor foradjusting said restriction to maintain a desired pressure drop acrossthe flow-controlling means, means for varying said control factor tovary the maintained pressuredrop across the flow-controlling means, and

means responsive to the negative pressure between the suction device andsaid restriction for controlling the operation of the suction device tovary its pulling capacity to limit the degree of said negative pressure.

m 4. The combination with flow-controlling means and means for supplyinggas at a constant substantially atmospheric pressure to theflowcontrolling means and a suction device for drawing the gas throughthe flow-controlling means,

oi means providing an adjustable restriction in means, means adjustablefor varying the drop in pressure across the flow-controlling meansmaintained by said pressure responsive means, and means responsive tothe negative pressure between the suction device and said restrictionfor controlling the operation of the suction device to ,vary its pullingcapacity to limit the degree of said negative pressure. 7 A

5. The combination with flow-controlling means and means for supplyinggas at a constant substantially atmospheric pressure to theflowcontrolling means and a suction device connected to draw the gasthrough the flow-controlling means, of means providing an adjustablerestriction in the connecting passage between the suction device and theflowcontrolling means, motor means for adjusting said restriction, andmeans responsive to variations in the negative pressure between saidrestriction and the flow-controlling means ior controlling the operationor said motor means to maintain said negative pressure constant.

6. The combination with flow-controlling means and means for supplyinggas at a constant substantially atmospheric pressure to the flowcontrolling means and a suction device for drawing the gas through theflow-controlling means, of a float chamber connectedbetween theflow-controlling means and the suction device, means providing anadjustable restriction for controlling the flow of gas from, saidchamber; motor means for adjusting said restriction, means formaintaining water in said chamber under a negative head, and a float insaid chamber for controling the operation of said motor means accordingto' the negative pressure and resulting water level in said chamber toclose the restriction when the water rises above a predetermined level,andto open the restriction when the water means and means forsupplyinggas at a constant substantially atmospheric pressure to theflow-controlling'means and a suction device for drawing the gas .throughthe flow-controlling means, co! 2. float chamber connected between theflow-contfiolling means and the suction device, means providing anadjustable restriction for controlling the flow of gas from saidchamber, a control member for adjusting said restriction, means tendingto move said member in one direction to open the restriction, means forsupplying liquid pressure to move said member in the other direction toclose the restriction, means for maintaining water in said chamber undera negative head, a float in the chamber, and means operated by saidfloat for controlling said liquid pressure.

,8. The means and means for supplying gas at a constant substantiallyatmospheric pressure to the flow-controlling means and a suction deviceconnected to draw the gas through the flow-controlling means, of a floatchamber connected be- 'tween the flow-controlling means and the suctiondevice, a valve for controlling the flow of gas combination withflow-controlling from said chamber, an operating member connected tosaid valve, means tending to move said member in the direction to openthe valve,

a pressure chamber a part of the wall of which is formed by saidoperating member and pressure in whichtends to move theoperating memberin the direction to close the valve, means for supplying water to saidpressure chamber at a constant flow rate, an outlet passage from thepressure ciamber discharging into the float chamber, means formaintaining a negative head on the water in the float chamber comprisingan overflow tube the lower end of which is connected to'the lowerpart-of the float chamber to form a U-tube and means for maintaining anegative pressure on the overflow end of the overflow tube, means forvarying said negative pressure to vary said negative head, a float inthefloat chamber, and a valve for controlling said outlet passagecontrolled by said float. I

9. The combination with a suction device and means providing a gaspassage leading to the suction device, of means; providing an ad ust-'able restriction in said passage, means for automatically adjusting saidrestriction to maintain a desired negative pressure in said passage. atthe inlet-side of the restriction, means adjustable for varying thenegative pressure maintained by said automatic means, and means forautomat1-,

cally controlling the suction device to vary its pulling capacity withvariation in the rate of gas flow in said passage.

10. The combination with a water and means for supplying water underpressure for operating the aspirator and means providing a gas suctionpassage leading to the aspirator, of a valve for regulating the pressureof water supplied to the aspirator, a container, means for supplying asmall continuous flow of water to the container, means providing apassage leading from the container upward to the suction passage,- andmeans for controlling said valve according to the amount of water in thecontainer.

11. The combination with a water aspirator and means for supplying waterunder pressure for operating the aspirator and means providing aspiratora gas passage leading to the aspirator, of a .valve for regulating theoperating pressure on the aspirator, a container, means for supplying asmall continuous flow of water to the container, means providing a smallpassage from the container upward to the suction passage, a lever bywhich said container is carried, means for applying to the lever inopposition to the weight of the water in the container a force whichvaries with the operating pressure on the aspirator, a pressure chamber,means responsive to the pressure in said pressure chamber for adjustingsaid valve, means for supplying water at a constant flow rate to saidpressure chamber, an outlet passage for said water, and a valve forcontrolling said outlet passage controlled by said lever.

12. The combination with a gas flow passage having a flow-controllingmeans therein and means for supplying gas at a controlled pressure tosaid flow-controlling means, of a suction device for drawing the gasthrough the flow-com trolling means, and means responsive to variationsin the negative pressure at the intake side of the suction device forcontrolling the operation of the suction device to vary its pullingcapacity to maintain said negative pressure substantially constant forvarying rates of gas flow. 13. The combination with flow-controllingmeans and means for supplying gas at a constant pressure to theflow-controlling means, of a suction device for drawing the gas throughthe flow-controlling means, means providing a restriction in the flowpassage between the flowcontrolling means and the suction deviceadjustable for determining the negative pressure transmitted to theflow-controlling means, and means responsive to variations in thenegative pressure between the suction device and said restriction forcontrolling the operation of the suction device to vary its pullingcapacity to maintain said negative pressure substantially constant.

GEORGE M. BOOTH.

